UNIVERSITY    OF    CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL    EXPERIMENT   STATION 

BERKELEY,    CALIFORNIA 

CIRCULAR  306 

May,  192G 

A  GENERAL  PURPOSE  SOIL  AUGER 
AND  ITS  USE  ON  THE  FARM 

STANLEY  W.  COSBY 


In  any  investigation  of  the  soil,  particularly  one  concerned  with 
the  production  of  crops,  it  is  highly  important  to  examine  the  subsoil 
zones  in  which  root  development  occurs  and  to  determine  the  presence 
of  conditions  favorable  or  unfavorable  for  plant  growth.  For  such 
an  examination  it  has  been  found  most  desirable  to  make  use  of  some 
soil  sampling  tool  (such  as  the  one  described  herein)  that  is  effective 
for  the  purpose,  readily  used,  and  easily  transported. 

TYPES   OF   SOIL   AUGERS 

Several  types  of  soil  sampling  tools  have  been  designed,  among 
the  more  important  being  the  "worm"  augers,  "post-hole"  augers, 
and  the  "soil  tubes."  Each  of  these  tools  appears  best  suited  for  some 
specific  purpose.  The  soil  tube  is  used  primarily  by  the  scientist  and 
investigator  who  must  have  accurate  and  uncontaminated  soil  samples 
for  laboratory  study,  while  the  post-hole  auger  has  been  found  best 
suited  to  sampling  certain  of  the  very  dry  and  coarse  soils.  The  worm 
auger  (fig.  1)  has  proved  under  a  wide  range  of  field  conditions 
to  be  the  best  general  purpose  auger  and  one  that  is  particularly 
suited  to  the  farmer's  use.  In  soil  survey  work  by  the  federal  and 
state  governments  this  auger  is  used  almost  exclusively  and  it  has 
become  known  as  the  ' '  Bureau  of  Soils ' '  type  of  auger. 

This  auger  is  being  offered  for  sale  at  the  present  time  by  several 
manufacturers  at  prices  ranging  between  seven  and  twelve  dollars. 
A  blacksmith,  or  anyone  handy  with  tools,  can  make  such  an  auger 
from  the  directions  given  below. 


DIRECTIONS    FOR    MAKING    A    SOIL    AUGER 


/"PiPE 


\ 


■Bit 


-Weld 


A" Pod 


The  side  cutting  edges  and  the  screw  point  (A  and  B  in  fig.  2)  are 
removed  from  a  li/o-inch  carpenter's  standard  wood  bit  and  the  pitch 
of  the  worm,  between  C  and  D  in  figure  2,  is  made  slightly  steeper. 
In  making  the  latter  change  the  bit  is  heated  and  drawn  out  on  the 
round  point  of  the  anvil,  a  process  that  tends  to  make  it  somewhat 
fish-tailed  in  shape  (fig.  3).  Finishing  touches 
can  be  given  with  a  file. 

The  square-tapered,  upper  end  of  the  bit  is 
then  removed  and  the  shank  welded  to  a  six-foot 
length  of  %  or  %-inch  steel  rod.  The  handle  at 
the  top  is  best  made  by  attaching  two  6-inch 
pieces  of  1-inch  pipe  to  the  rod  with  an  ordinary 
Tee-coupling. 

The  auger  may  be  made  in  two  or  more  sec- 
tions for  greater  convenience  in  carrying  it  from 
one  place  to  another  by  putting  in  a  sleeve- 
coupling  at  each  joint,  as  shown  in  figure  1.  This 
coupling  should  be  strong;  the  hexagonal  wind- 
mill pump  rod  connection  has  been  found  most 
satisfactory  for  this  purpose.  A  short  section 
near  the  ends  of  each  rod  may  be  slightly  flat- 
Aero motor  tened  to  make  it  easier  to  grip  with  the  wrench 
"i*  iSleevi  when  uncoupling  the  auger.  The  threading  on 
the  ends  of  the  sections  should  extend  for  a 
sufficient  distance  to  permit  jamming  the  ends 
together  within  the  coupling.  When  the  auger 
is  thus  screwed  tightly  together  it  will  withstand 
considerable  strain  in  "backing-out"  without 
uncoupling.  It  is  not  advisable  to  drill  a  hole 
through  the  coupling  and  the  rod  for  a  rivet  or 
pin,  as  it  weakens  the  rod  and  is  unnecessary  if 
the  auger  is  properly  made. 

HOW    TO    USE    A    SOIL    AUGER 

In  boring  a  hole  with  this  type  of  auger,  the 

surface  trash  and  loose  soil  should  be  removed 

to  prevent  it  from  falling  into  the  hole.      Twist 

the  auger  vertically  downward  about  six  inches, 

place  the  feet  close  to  the  auger  on  each  side 

and  pull  straight  upward,  at  the  same  time 

giving  the  auger  a  quarter  turn  to  the  right  to 

break  free  the  core  of  soil.    To  remove  the  soil 

from   the    auger,   hold   it   near   the   point   of 


COC/PUNG 


r  "Pod 


Tee 
/Coupling 


^m 


f/6.  J.  /fssen^c/ 


balance  with  the  right  hand,  place  the  thumb  and  first  finger  of  the 
left  hand  at  the  tip  of  the  bit  and  twist  the  entire  anger  with  the 
right  hand.  This  will  canse  the  bit  to  turn  through  the  fingers  and 
drop  the  soil  into  the  left  hand.  In  particularly  dry  soils  it  may  be 
necessary  to  pour  a  small  amount  of  water  into  the  hole  to  moisten 
the  soil  and  permit  the  ready  removal  of  the  sample.  Do  not  twist 
the  auger  too  deeply  before  removal,  as  in  heavy  soils  it  may  prove 
impossible  to  pull  out  a  deep  core.  In  very  tough  soils  better  progress 
can  be  made  by  boring  in  a  half  turn  of  the  auger,  pulling  this  up  an 
inch  or  two  to  cut  it  loose,  then  boring  in  again,  thus  filling  the  worm 
with  soil  without  having  to  break  it  all  loose  with  one  effort. 


/="/<£  2  -  WOOD  BIT 


F/6.  3   -  SOIL  BIT 


SOME  FARM  USES  FOR  THE  SOIL  AUGER 

The  soil  auger  is  adapted  to  a  great  many  uses  on  the  farm.  These 
range  from  a  detailed  inspection  of  land  Avhich  the  farmer  contem- 
plates purchasing  or  a  study  of  soil  conditions  for  the  laying  out  of 
his  fields  and  orchards,  to  the  acquisition  of  soil  knowledge  on  which 
to  base  his  various  cultural  methods  and  irrigation  practices. 

Although  the  surface  of  the  soil  may  have  a  uniform  appearance, 
the  subsoil  frequently  shows  marked  variation  within  short  distances, 
either  in  a  vertical  or  horizontal  direction.  This  is  particularly  true 
in  the  case  of  our  stream-laid  soils.  In  the  more  recent  depositions  the 
vagaries  of  the  depositing  streams  have  produced  numerous  strips  and 
bodies  of  soil  having  wide  textural  differences ;  a  very  heavy  clay  sub- 
soil strata  may  adjoin  a  coarse  sandy  or  gravelly  remnant  of  a  former 
channel  which  has  been  covered  by  later  depositions.  In  our  old 
alluvial  soils,  marked  changes  in  subsoil  textures  are  not  so  abrupt 


in  a  horizontal  plane  as  they  are  in  a  vertical  direction,  the  initial 
differences  due  to  deposition  having*  been  largely  obscured  by  later 
modifications  due  to  weathering.  Generally  this  period  of  modification 
has  produced  a  much  heavier-textured  subsoil,  one  that  may  be  very 
compact  and  relatively  impervious  to  the  penetration  of  moisture  and 
plant  roots.  The  more  extreme  developments  of  these  processes  have 
resulted  in  the  formation  of  the  hard  cemented  subsoil  zone,  com- 
monly known  as  "hardpan."  The  various  subsoil  conditions  are 
seldom  apparent  from  surface  indications  and  yet  their  presence  has 
a  profound  influence  on  the  production  of  crops. 

In  purchasing  a  farm,  the  intelligent  buyer  will  endeavor  to  secure 
extensive  information  concerning  it  and  to  evaluate  this  in  terms  of 
crop-profits.  The  most  reliable  and  economical  method  of  securing 
information  regarding  the  soils  consists  of  a  systematic  series  of 
borings  over  the  entire  property  in  order  to  determine  the  soil  and 
subsoil  characteristics.  Such  borings  will  show  the  soil  variations  and 
may  be  used  subsequently  in  the  construction  of  a  map,  or  lay-out, 
to  determine  the  location  of  the  different  crops  to  be  planted.  This 
will  lead  to  the  crops  being  situated  on  those  soils  which  are  best 
suited  to  their  production. 

On  a  farm  which  has  already  been  developed,  the  soil  auger  is  a 
valuable  aid  in  cultural  practices,  particularly  in  the  case  of  irri- 
gation. By  a  study  of  the  moisture  conditions  both  before  and  after 
irrigation,  information  can  be  secured  to  determine  the  time  of 
application  of  water  and  the  most  desirable  method  to  follow.  The 
farmer  can  ascertain  the  depths  to  which  the  water  is  penetrating  and 
avoid  the  undesirable  features  of  too  shallow  or  of  too  deep  a  distri- 
bution, making  the  application  according  to  the  root-depths  of  his 
crop.  He  can  vary  his  applications  in  different  parts  of  his  orchard, 
or  field,  according  to  the  local  soil  variations.  By  a  frequent  obser- 
vation of  the  moisture  in  his  soil,  he  can  maintain  it  more  nearly  at 
the  desirable  point  than  by  judging  from  surface  indications,  or  by 
a  rule-of-thumb  schedule. 

Over-wet  soils,  high  water  tables,  and  the  need  for  artificial 
drainage  can  be  readily  determined  with  this  tool.  Many  other  uses 
might  be  suggested,  such  as  studying  small  areas  where  failure  of 
crops  may  be  due  to  some  previously  undiscovered  subsoil  condition 
or  moisture  variation,  or  determining  the  proper  location  for  various 
farm  structures,  wells,  pits,  and  other  excavations. 

This  type  of  soil  auger  is  light,  easily  carried,  and  rapid  and  easy 
in  operation,  features  that  are  essential  if  the  tool  is  to  be  used  as 
extensively  and  continuously  as  is  necessary  in  controlling  irrigation 
and  interpreting  crop  responses  to  soil  conditions. 


